President Richard M. Nixon, First Lady Pat Nixon, and newlyweds Tricia Nixon Cox and Edward Cox stand in the receiving line at the White House on June 12, 1971, following their wedding ceremony in the Rose Garden. Newscom/FILE

Former President Harry Truman is seen with his wife Bess on their wedding day in Independence, Mo., on June 28, 1919. Harry S. Truman Library and Museum/UPI/Newscom/FILE

Former President Franklin D. Roosevelt's wife Eleanor is seen here on her wedding day. Newscom/FILE

President Theodore Roosevelt is seen here with his daughter, Alice, and her husband Nicholas Longworth on their wedding day at the White House. Newscom/FILE

Marc Mezvinsky, left, with his new mother-in-law Hillary Rodham Clinton, his bride Chelsea and father-in-law former President Bill Clinton after the couples wedding July 31, in Rhinebeck, N.Y. Barbara Kinney/Genevieve de Manio Photography/AP

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Sophisticated and lethal, growing in number, Islamic State and other extremist groups won't become a global force. Here's why.

BySeth G. Jones, ContributorMarch 29, 2015

Raqqa Media Center of the Islamic State Group/AP

Mullah Abdul Rauf Khadim looked like any ubiquitous insurgent commander in southern Afghanistan. He had a sunbaked complexion, serried black beard, charcoal eyes, and the usual accessory – an AK-47 slung over his shoulder.